U.S. patent application number 13/390492 was filed with the patent office on 2012-06-07 for communications system.
Invention is credited to Milena Filipovic, Francesca Serravalle.
Application Number | 20120142356 13/390492 |
Document ID | / |
Family ID | 41171521 |
Filed Date | 2012-06-07 |
United States Patent
Application |
20120142356 |
Kind Code |
A1 |
Serravalle; Francesca ; et
al. |
June 7, 2012 |
COMMUNICATIONS SYSTEM
Abstract
A user communications device, such as a mobile telephone,
obtains and reports capability information to a serving base
station. The capability information identities if a neighbouring
UTRAN base station is HSPA/EDCH capable. The serving E-UTRAN base
station can use this information to control handover decisions and
load balancing performed thereby.
Inventors: |
Serravalle; Francesca;
(Minato-ku, GB) ; Filipovic; Milena; (Minato-ku,
JP) |
Family ID: |
41171521 |
Appl. No.: |
13/390492 |
Filed: |
August 10, 2010 |
PCT Filed: |
August 10, 2010 |
PCT NO: |
PCT/JP2010/063792 |
371 Date: |
February 14, 2012 |
Current U.S.
Class: |
455/436 |
Current CPC
Class: |
H04W 36/0016
20130101 |
Class at
Publication: |
455/436 |
International
Class: |
H04W 36/00 20090101
H04W036/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 17, 2009 |
GB |
0914380.1 |
Claims
1. An E-UTRAN base station having an Automatic Neighbour Relation
(ANR) function and comprising: a Neighbour Relation Table, NRT,
comprising cell information for cells that neighbour the base
station; and a measurement control module operable: i) to send a
mobile communications device a request to obtain cell information
for a neighbouring cell within communication range of the mobile
communications device; ii) to receive a report from the mobile
communications device including the requested cell information; and
iii) to store information in the NRT in dependence upon the report
received from the mobile communications device; wherein the base
station is operable to receive data identifying if the neighbouring
cell is HSPA and/or EDCH capable and is operable to include the
received capability information in the NRT.
2. A base station according to claim 1, further comprising a
handover module operable to control handover of mobile
communications devices to and from the base station and wherein the
handover module is operable to control handover of mobile
communications devices to another base station using the capability
information stored in the NRT.
3. A base station according to claim 2, wherein the handover module
is operable to use subscriber information and the capability
information stored in the NRT to select a target cell for the
handover.
4. A base station according to claim 3, wherein the handover module
is operable to select an HSPA/EDCH capable cell over a less capable
cell even if signal measurements obtained by the mobile
communications device for the less capable cell are better than
signal measurements obtained by the mobile communications device
for the HSPA/EDCH capable cell.
5. A base station according to claim 1, further comprising a load
balancing module operable to perform load balancing with
neighbouring cells and wherein the load balancing module is
operable to use the cell capability information to identify
neighbouring HSPA capable cells and to begin load balancing
measurements with them.
6. A base station according to claim 1, further comprising a load
balancing module operable to perform load balancing with
neighbouring cells and wherein the load balancing module is
operable to use the cell capability information to select the
neighbouring cells with which to perform load balancing.
7. A base station according to claim 1, further comprising a load
balancing module operable to perform load balancing with
neighbouring cells and wherein the load balancing module is
operable to segregate mobile communications devices that it is
serving into HSPA capable mobile communications devices and voice
only mobile communications devices and is operable to use the cell
capability information to cause handover of HSPA capable mobile
communications devices to HSPA capable cells and voice only mobile
communications devices to handover to HSPA non-capable cells.
8. A base station according to claim 1, wherein the base station is
operable to receive the cell capability information from the mobile
communications device or from a node coupled to the base
station.
9. A mobile communications device comprising: a transceiver
operable to transmit signals to and to receive signals from one or
more base stations; a measurement module operable to receive a
request from a serving base station, via the transceiver, to obtain
cell information for a neighbouring cell and to obtain the cell
information from signals broadcast by the neighbouring cell that
are received by the transceiver; and a reporter module operable to
send the serving base station, using the transceiver, a report that
includes the obtained cell information; wherein the received
request requests the mobile communications device to report whether
or not the neighbouring cell is HSPA and/or EDCH capable, wherein
the measurement module is operable to obtain this capability
information from the signals broadcast by the cell and wherein the
reporter module is operable to include the obtained cell capability
information in the report sent back to the serving base
station.
10. A method performed by an E-UTRAN base station having an
Automatic Neighbour Relation (ANR) function, the method comprising:
storing cell information for cells that neighbour the base station
in a Neighbour Relation Table, NRT; sending a mobile communications
device a request to obtain cell information for a neighbouring
cell; receiving a report from the mobile communications device
including the requested cell information; and storing information
in the NRT in dependence upon the report received from the mobile
communications device; wherein the method further comprises
receiving data indicating if the neighbouring cell is HSPA and/or
EDCH capable and storing information in the NRT for the
neighbouring cell identifying if the neighbouring cell is HSPA
and/or EDCH capable.
11. A method performed by a mobile communications device, the
method comprising: receiving a request from a serving base station
to obtain cell information for a neighbouring cell; obtaining the
requested cell information from signals broadcast by the
neighbouring cell; and sending the serving base station a report
that includes the obtained cell information; wherein the received
request requests the mobile communications device to report whether
or not the neighbouring cell is HSPA and/or EDCH capable, wherein
the obtaining obtains this capability information from the signals
broadcast by the cell and wherein the report that is sent to the
serving cell includes the obtained cell capability information.
12. An E-UTRAN base station having an Automatic Neighbour Relation
(ANR) function and comprising: means for storing cell information
for cells that neighbour the base station in a Neighbour Relation
Table, NRT; means for sending a mobile communications device a
request to obtain cell information for a neighbouring cell; means
for receiving a report from the mobile communications device
including the requested cell information; and means for storing
information in the NRT in dependence upon the report received from
the mobile communications device; wherein the base station further
comprises means for receiving data indicating if the neighbouring
cell is HSPA and/or EDCH capable and means for storing information
in the NRT for the neighbouring cell identifying if the
neighbouring cell is HSPA and/or EDCH capable.
13. A mobile communications device comprising: means for receiving
a request from a serving base station to obtain cell information
for a neighbouring cell; means for obtaining the requested cell
information from signals broadcast by the neighbouring cell; and
means for sending the serving base station a report that includes
the obtained cell information; wherein the received request
requests the mobile communications device to report whether or not
the neighbouring cell is HSPA and/or EDCH capable, wherein the
means for obtaining is operable to obtain this capability
information from signals broadcast by the cell and wherein the
means for sending a report is operable to send a report to the
serving cell that includes the obtained cell capability
information.
14. (canceled)
15. A non-transitory computer readable recording medium storing
computer implementable instructions for causing a programmable
computer device to become configured as the base station according
to claim 1.
16. A non-transitory computer readable recording medium storing
computer implementable instructions for causing a programmable
computer device to become configured as the mobile communications
device according to claim 9.
17. A base station according to claim further comprising a load
balancing module operable to perform load balancing with
neighbouring cells and wherein the load balancing module is
operable to use the cell capability information to identify
neighbouring HSPA capable cells and to begin load balancing
measurements with them.
18. A base station according to claim 3, further comprising a load
balancing module operable to perform load balancing with
neighbouring cells and wherein the load balancing module is
operable to use the cell capability information to identify
neighbouring HSPA capable cells and to begin load balancing
measurements with them.
19. A base station according to claim 4, further comprising a load
balancing module operable to perform load balancing with
neighbouring cells and wherein the load balancing module is
operable to use the cell capability information to identify
neighbouring HSPA capable cells and to begin load balancing
measurements with them.
20. A base station according to claim 2, further comprising a load
balancing module operable to perform load balancing with
neighbouring cells and wherein the load balancing module is
operable to use the cell capability information to select the
neighbouring cells with which to perform load balancing.
21. A base station according to claim 3, further comprising a load
balancing module operable to perform load balancing with
neighbouring cells and wherein the load balancing module is
operable to use the cell capability information to select the
neighbouring cells with which to perform load balancing.
Description
TECHNICAL FIELD
[0001] The present invention relates to mobile telecommunications
networks, particularly but not exclusively networks operating
according to the 3GPP standards or equivalents or derivatives
thereof.
BACKGROUND ART
[0002] Mobile telecommunications networks enable users of User
Equipment (UE) to communicate with other such users via one of a
number of base stations and a core network. Each base station
defines a number of cells of the network. In an active state a UE
is registered with the network and has an RRC (Radio Resource
Control) connection with a base station so that the network knows
which cell the UE belongs to and can transmit data to and receive
data from the UE. In the Long Term Evolution (LTE) of UTRAN (UMTS
Terrestrial Radio Access Network) referred to as E-UTRAN, in the
Active state, the handover procedure allows UEs to have service
continuity while moving between LTE cells and when moving to cells
of other RATs (Radio Access Technologies), such as UTRAN cells and
GERAN cells.
[0003] E-UTRAN base stations (referred to as eNBs) are able to
handover a UE to another E-UTRAN cell (Inter frequency handover) or
to a cell of another RAT (Inter RAT handover) only if the source
cell is aware of the existence of the target cell. This information
may be configured into the base station. However, due to the cost
of doing this and due to the continuous updating of this
configuration information, an automatic procedure has been defined
in the 3GPP standards documentations (see TS 36.300 V9.0.0). This
automatic procedure is referred to as ANR (Automatic Neighbour
Relation) and relies on the UEs providing information to the
serving base station about cells that they detect. The present
invention relates specifically to improving the current ANR
proposal for E-UTRAN base stations.
DISCLOSURE OF INVENTION
[0004] An exemplary aspect of the present invention provides an
E-UTRAN base station having an Automatic Neighbour Relation (ANR)
function and including: a Neighbour Relation Table, NRT, comprising
cell information for cells that neighbour the base station; and a
measurement control module operable: i) to send a mobile
communications device a request to obtain cell information for a
neighbouring cell within communication range of the mobile
communications device; ii) to receive a report from the mobile
communications device including the requested cell information; and
iii) to store information in the NRT in dependence upon the report
received from the mobile communications device; wherein the base
station is operable to receive data identifying if the neighbouring
cell is HSPA and/or EDCH capable and is operable to include the
received capability information in the NRT. The cell capability
information may be provided by the mobile communications device or
by an Operations & Management node (or from some node within
the network).
[0005] The base station also includes a handover module for
controlling handover of mobile communications devices to and from
the base station and the handover module can control handover of
mobile communications devices to other base stations using the
reported capability information. This may be achieved by using the
reported capability information to select a target cell for the
handover. The handover module may select an HSPA/EDCH capable cell
over a less capable cell even if signal measurements obtained by
the mobile communications device for the less capable cell are
better than signal measurements obtained by the mobile
communications device for the HSPA/EDCH capable cell.
[0006] The base station may also include a load balancing module
that performs load balancing with neighbouring cells and that uses
the cell capability information to identify neighbouring HSPA
capable cells and to begin load balancing measurements with them.
The load balancing module may, in addition or alternatively, use
the cell capability information to select the neighbouring cells
with which to perform load balancing. For example, the load
balancing module may segregate mobile communications devices that
it is serving into HSPA capable mobile communications devices and
voice only mobile communications devices and then use the cell
capability information to cause handover of HSPA capable mobile
communications devices to HSPA capable cells and voice only mobile
communications devices to handover to HSPA non-capable cells.
[0007] The present invention also provides a mobile communications
device comprising: a transceiver operable to transmit signals to
and to receive signals from one or more base stations; a
measurement module operable to receive a request from a serving
base station, via the transceiver, to obtain cell information for a
neighbouring cell and to obtain the cell information from signals
broadcast by the neighbouring cell that are received by the
transceiver; and a reporter module operable to send the serving
base station, using the transceiver, a report that includes the
obtained cell information; wherein the received request requests
the mobile communications device to report whether or not the
neighbouring cell is HSPA and/or EDCH capable.
[0008] The present invention also provides a method performed by an
E-UTRAN base station having an Automatic Neighbour Relation (ANR)
function, the method comprising: storing cell information for cells
that neighbour the base station in a Neighbour Relation Table, NRT;
sending a mobile communications device a request to obtain cell
information for a neighbouring cell; receiving a report from the
mobile communications device including the requested cell
information; and storing information in the NRT in dependence upon
the report received from the mobile communications device; wherein
the method further comprises receiving data indicating if the
neighbouring cell is HSPA and/or EDCH capable and storing
corresponding capability information in the NRT.
[0009] The present invention also provides a method performed by a
mobile communications device, the method comprising: receiving a
request from a serving base station to obtain cell information for
a neighbouring cell; obtaining the requested cell information from
signals broadcast by the neighbouring cell; and sending the serving
base station a report that includes the obtained cell information;
wherein the received request requests the mobile communications
device to report whether or not the neighbouring cell is HSPA
and/or EDCH capable.
[0010] The present invention also provides software and/or firmware
for programming a general purpose base station and a general
purpose mobile communications device to operate in accordance with
the present invention. This software may be provided on a recording
medium or on a signal obtained from a computer network.
[0011] The invention also provides, for all methods disclosed,
corresponding computer programs or computer program products for
execution on corresponding user communications devices or base
stations. The invention also provides user communications devices
and base stations configured or operable to implement the methods
and components thereof) and methods of updating these.
[0012] Embodiments of the invention will now be described, by way
of example, with reference to the accompanying drawings, in
which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates schematically a cellular
telecommunications system to which exemplary embodiments of the
invention may be applied;
[0014] FIG. 2 is a functional block diagram to show some of the
functionality of a mobile telephone forming part of the system
shown in FIG. 1;
[0015] FIG. 3 is a functional block diagram to show some of the
functionality of a base station forming part of the system shown in
FIG. 1;
[0016] FIG. 4 illustrates the signalling that is performed using
the improved ANR procedure proposed by an exemplary embodiment of
the present invention,
[0017] FIG. 5 illustrates reporting of parameter in UE only when
requested by the eNB; and
[0018] FIG. 6 illustrates an Automatic Neighbour Relation Function
in case of UTRAN detected cell.
BEST MODE FOR CARRYING OUT THE INVENTION
[0019] With reference to the drawings in general, it should be
understood that any functional block diagrams are intended simply
to show the functionality that exists within the device and should
not be taken to imply that each block shown in the functional block
diagram is necessarily a discrete or separate entity. The
functionality provided by a block may be discrete or may be
dispersed throughout the device or throughout a part of the device.
In addition, the functionality may incorporate, where appropriate,
hardwired elements, software elements or firmware elements or any
combination of these.
Overview
[0020] FIG. 1 schematically illustrates a mobile (cellular)
telecommunication system 1 in which users of mobile telephones 3-0,
3-1, 3-2 and 3-3 can communicate with other users (not shown) via
one of the base stations 5-1 or 5-2 and a telephone core network 7.
In the system illustrated in FIG. 1, the base station 5-1 is a
UTRAN base station and it is currently serving mobile telephone 3-0
and base station 5-2 is an E-UTRAN base station and it is currently
serving mobile telephones 3-1, 3-2 and 3-3. Each base station 5
operates a number of base station cells, each having a number of
uplink and downlink communications resources (sub-carriers, time
slots etc) that are available for wireless communication between
the mobile telephones 3 and the corresponding base station 5. In
this exemplary embodiment, it will be assumed for the sake of
simplicity of explanation, that each base station 5 operates a
single cell. The base stations 5 allocate downlink resources to
each mobile telephone 3 depending on the amount of data to be sent
to the mobile telephone 3. Similarly, the base stations 5 allocate
uplink resources to each mobile telephone 3 depending on the amount
and type of data the mobile telephone 3 has to send to the base
station 5.
[0021] The mobile telephones 3 have connected and idle modes or
states. In the connected state a mobile telephone 3 is registered
with a serving base station 5 and has an RRC (Radio Resource
Control) connection with the base station 5 so that the network
knows to which cell the mobile telephone 3 belongs. E-UTRAN base
stations (such as base station 5-2) can request a connected mobile
telephone 3 that it is serving to make measurements on neighbouring
cells so that it can maintain an up to date list of all its
neighbouring cells. To do this, the serving E-UTRAN base station
5-2 schedules appropriate measurement gaps between downlink and
uplink transmissions to/from the mobile telephone 3, during which
the mobile telephone 3 can make and report on the measurements
requested by the E-UTRAN base station 5-2. The E-UTRAN base station
5-2 can then use this information to control handover
decisions.
[0022] At present, when reporting on a UTRAN cell, the mobile
telephone 3 can report the cell Global Id (CGI), the Location Area
Code (LAC) and the Routeing Area Code (RAC) of the UTRAN cell. The
present embodiment proposes to augment the information that the
E-UTRAN base station 5-2 is able to request and in particular to
include capability information for the UTRAN cell. More
specifically, the embodiment proposes that the E-UTRAN base station
5-2 can request the mobile telephone 3 to report on whether the
UTRAN cell is HSPA (High Speed Packet Access) and/or EDCH (Enhanced
Dedicated CHannel) capable. This additional information can allow
the base station to make better handover decisions and to use the
information to make load balancing decisions.
Mobile Telephone
[0023] FIG. 2 is a functional block diagram of a mobile telephone 3
shown in FIG. 1. As shown, the mobile telephone 3 has a transceiver
circuit 21 that is operable to transmit signals to and to receive
signals from a base station 5 via one or more antenna 23. The
mobile telephone 3 has a controller 27 to control the operation of
the mobile telephone 3 and a SIM (Subscriber Identity Module) 22.
The controller 27 is associated with a memory 29 and is coupled to
the transceiver circuit 21 and to a user interface 28 having a
loudspeaker 28a, a microphone 28b, a display 28c and a keypad 28d.
Although not necessarily shown in FIG. 2, the mobile telephone 3
will of course have all the usual functionality of a cellular
telephone and this may be provided by any one or any combination of
hardware, software and firmware, as appropriate. Software may be
pre-installed in the memory and/or may be downloaded via the
telecommunications network or from a removable data storage device
(RMD) 23, for example.
[0024] The controller 27 is configured to control overall operation
of the mobile telephone 3 by, in this example, program instructions
or software instructions stored within memory 29. As shown, these
software instructions include, among other things, an operating
system 31, a cell selector/reselector module 33, a reporter module
34 and a measurement module 35. The cell selector module 33 is
operable to enable selection and reselection of cells in accordance
with cell selection/reselection parameters provided by the base
station 5. The measurement module 35 is operable to make
measurements and obtain information on neighbouring cells that are
within range of the mobile telephone 3, when instructed to do so by
the serving base station 5. The reporter module 34 is operable to
report the measurements and the information obtained for the
neighbouring cells to the serving base station 5.
[0025] As shown in FIG. 2, the memory 29 also includes a data store
36 for temporarily storing the information obtained by the
measurement module 35 until it is reported to the serving base
station 5. The information to be reported includes the Cell Global
ID (CGI) 36-1 of the cell, the Location Area Code 36-2 of the cell,
the Routeing Area Code 36-3 of the cell and HSPA/EDCH capability
information 36-4.
Base Station
[0026] FIG. 3 shows a functional block diagram of the E-UTRAN base
station 5-2 shown in FIG. 1. As shown, the E-UTRAN base station 5-2
has a transceiver circuit 41 to transmit signals to and to receive
signals from the mobile telephones 3 via one or more antenna 43, a
network interface 44 to transmit signals to and receive signals
from the core network 7 and a base station interface 45 to transmit
signals to and to receive signals from other E-UTRAN base stations
(not shown). The E-UTRAN base station 5-2 has a controller 47 to
control the operation of the base station. The controller 47 is
associated with a memory 49. Although not necessarily shown in FIG.
3, the E-UTRAN base station 5-2 will of course have all the usual
functionality of a cellular telephone network base station and this
may be provided by any one or any combination of hardware, software
and firmware, as appropriate. Software may be pre-installed in the
memory 49 and/or may be downloaded via the telecommunications
network or from a removable data storage device (RMD), for
example.
[0027] The controller 47 is configured to control overall operation
of the E-UTRAN base station 5 by, in this example, program
instructions or software instructions stored within memory 49. As
shown, these software instructions include, among other things, an
operating system 51, a measurement control module 52, a handover
module 53 and a load balancing module 54. The measurement control
module 52 is operable to request a mobile telephone 3 to make
specified measurements and obtain specified information about
neighbouring cells and to receive the reports back from the mobile
telephone 3. The measurement control module 52 uses the information
received back from the mobile telephones 3 to maintain (and update)
a Neighbour Relation Table (NRT) 55 that is stored within a data
store 56 of the memory 49. The handover module 53 is operable to
control the handover of a mobile telephone 3 from the current
E-UTRAN cell to another cell. The handover module 53 uses cell
measurement information from the mobile telephone 3, the
information stored in the NRT 55 and subscriber profile information
57 (also stored in the data store 56) to select a suitable target
cell for the mobile telephone 3. The load balancing module 54 is
operable to provide load information for the cell to neighbouring
cells, to receive load information from neighbouring cells and to
make decisions on whether or not load balancing procedures should
be implemented to share the load over the neighbouring cells. The
load balancing module 54 uses the information stored in the NRT 55
to identify the neighbouring cells and to control the load
balancing procedure.
[0028] In the above description, the base station 5 and the mobile
telephones 3 are described for ease of understanding as having a
number of discrete functional components or modules (such as the
measurement module, cell selector module, handover module, load
balancing module, reporter module etc). Whilst these modules may be
provided in this way for certain applications, for example where an
existing system has been modified to implement the invention, in
other applications, for example in systems designed with the
inventive features in mind from the outset, these modules may be
built into the overall operating system or code and so these
modules may not be discernible as discrete entities.
Operation
[0029] In operation of the system described above, when a mobile
telephone 3 is in a connected mode such as when making a call and
is being served by the E-UTRAN base station 5-2, the base station
5-2 will ask the mobile telephone 3 to make measurements and obtain
information about neighbouring cells. Gaps in the normal uplink and
downlink transmissions will be scheduled by the base station 5-2 to
allow the mobile telephone 3 to perform these measurements and to
report the results back to the serving base station 5-2 without
interfering with the current call. The sequence of events is
illustrated in FIG. 4. As shown, at step 1, the serving base
station 5-2 sends the mobile telephone 3 a Report Neighbour
Request. The request identifies one or more RATs and frequencies on
which the measurements are to be made. In the example illustrated
in FIG. 4, the request includes the RAT and frequency for just
UTRAN base station 5-1. In response to receiving the request, the
mobile telephone 3 makes, in step 2, signal measurements on the
specified frequency according to the defined RAT and obtains the
physical cell ID for the detected cell. The mobile telephone 3 then
sends, in step 3, a Report Neighbour Response message back to the
base station 5-2 that includes the physical cell ID for the
detected cell and an indication of the signal level of the signal
received from the detected cell.
[0030] In response to receiving this report, the base station 5-2
may send the mobile telephone 3, in step 4, a Report Neighbour
Request asking the mobile telephone 3 to obtain the CGI, LAC and
RAC for the detected cell. In this embodiment, for UTRAN cells that
are detected, the base station 5-2 can also optionally request the
mobile telephone 3 to obtain information identifying if the UTRAN
cell is capable of High Speed Packet Access (HSPA) and/or has an
Extended Dedicated Channel (E-DCH). In step 5, the mobile telephone
3 obtains the requested information by reading the broadcast
channel (BCH) of the detected cell, which includes the requested
information as part of the broadcast system information. In step 6,
the mobile telephone 3 reports the requested information back to
the base station 5-2, which stores the information in the NRT
55.
[0031] Thus in this embodiment, the E-UTRAN base station 5-2 is
provided with the additional information about whether or not the
UTRAN cell is HSPA/EDCH capable. The E-UTRAN base station 5-2 can
then use this additional information in the flowing ways:
Handover Decision Algorithm
[0032] As discussed above, the handover module 53 makes decisions
about handing over the mobile telephone 3 when it is moving about
and between adjacent cells. Prior to performing the handover
process, the E-UTRAN base station 5-2 will request the mobile
telephone 3 to obtain and report on possible target cells for the
handover (based on signal measurements). With the additional
capability information previously provided by the above reporting
process, the handover module 54 can decide on the most appropriate
target cell, when the mobile telephone 3 reports more than one cell
as possible targets, based on the mobile telephone subscriber
profile information 57 (typically obtained at handover) and the
target cell capability. Thus if one of the target cells is a UTRAN
cell that is HSPA capable and the mobile telephone subscriber has
subscribed for high speed services, then the handover module 53 can
select the HSPA capable cell to be the target for the handover
instead of a less capable cell even though the signal measurements
for the less capable cell are better than those of the chosen
target cell.
Inter RAT Load Balancing SON
[0033] E-UTRAN base stations 5-2 are designed to form part of a so
called Self Organising Network (SON). SONs can automatically
change, configure and optimize the network coverage, cell size,
frequency allocation and bandwidth, based on changes in
interference, signal strength and traffic. Load balancing is one
aspect of a SON that allows the network to share the load across
the cells of the network. With the additional capability
information available for UTRAN cells, the load balancing module 54
can change the way that it performs load balancing procedures. For
example, the load balancing module 54 can use the obtained
capability information to identify neighbouring HSPA capable UTRAN
cells and to begin the load balancing measurements with them.
Alternatively, the load balancing module 54 may perform load
balancing only between E-UTRAN cells and HSPA capable UTRAN cells.
The load balancing module 54 may segregate the mobile telephones 3
into high rate telephones, HSPA capable telephones and voice only
telephones. In this case, the load balancing module 54 and the
handover module 53 may use the additional UTRAN capability
information to cause handover of the HSPA capable telephones to
HSPA capable UTRAN cells and voice only telephones to handover to
HSPA non-capable UTRAN cells or other RAT cells (eg GERAN
cells).
Modifications and Alternatives
[0034] Detailed embodiments have been described above. As those
skilled in the art will appreciate, a number of modifications and
alternatives can be made to the above exemplary embodiments whilst
still benefiting from the inventions embodied therein. By way of
illustration only a number of these alternatives and modifications
will now be described.
[0035] In the above exemplary embodiments, the mobile telephones
are cellular telephones. Other communications nodes or devices may
include user devices such as, for example, personal digital
assistants, laptop computers, web browsers, etc.
[0036] In the above exemplary embodiment, the mobile telephone
obtained and reported capability information to the serving base
station, specifically HSPA and/or EDCH capability information. In
an alternative exemplary embodiment, the mobile telephone (UE) may
report the cell ID for a new cell to the serving base station and
in turn, the serving base station may report to an Operations &
Management (O&M) node that a new neighbour relation has been
established. In response to receiving this message (or in response
to receiving a request from the base station), the O&M node may
return the HSPA and/or EDCH capability information back to the
serving base station for adding to the NRT table. Thus in this
exemplary embodiment, it is not the mobile telephone that reports
the HSPA/EDCH capability information to the base station.
[0037] In the above exemplary embodiments, a number of software
modules were described. As those skilled in the art will
appreciate, the software modules may be provided in compiled or
un-compiled form and may be supplied to the base station or to the
mobile telephone as a signal over a computer network, or on a
recording medium. Further, the functionality performed by part or
all of this software may be performed using one or more dedicated
hardware circuits. However, the use of software modules is
preferred as it facilitates the updating of base station 5 and the
mobile telephones 3 in order to update their functionalities.
[0038] Various other modifications will be apparent to those
skilled in the art and will not be described in further detail
here.
GLOSSARY of 3GPP Terms
[0039] UE--User Equipment--user communications device
RAT--Radio Access Technology
RAN--Radio Access Network
[0040] HO--Handover
eNodeB, eNB--E-UTRAN base station LTE--Long Term Evolution (of
UTRAN)
UTRAN--UMTS Terrestrial Radio Access Network
UMTS--Universal Mobile Telecommunications System
MME--Mobility Management Entity
BCH--Broadcast Channel
RRC--Radio Resource Control
SON--Self Organising Network
RRM--Radio Resource Management
LAC--Location Area Code
RAC--Routing Area Code
CGI--Cell Global ID
HSPA--High Speed Packet Access
E-DCH--Enhanced Dedicated Channel
[0041] The following is a detailed description of the way in which
the present inventions may be implemented in the currently proposed
3GPP LTE standard. Whilst various features are described as being
essential or necessary, this may only be the case for the proposed
3GPP LTE standard, for example due to other requirements imposed by
the standard. These statements should not, therefore, be construed
as limiting the present invention in any way.
Introduction
[0042] Purpose of this contribution is to propose an enhancement of
the ANR functionality so that the UE may report the IRAT
capability, i.e. HSDPA/HSPA capability, whenever requested from the
eNB.
[0043] The IRAT cell capability will be used by RRM, some examples
of use cases are listed in paragraph.
[0044] Paragraph three will give explanations on the solution and
finally paragraph four is a proposal of implementation in the
spec.
Use of Cell Capability
Background
[0045] Currently, ANR functionality foresee following parameters to
be reported by the UE for a potential target UTRAN neighbouring
cell: [0046] Cell Global id [0047] LAC [0048] RAC
[0049] It is believed that eNB RRM may benefit from the knowledge
of the target cell capability which may be reported by the UE as
part of ANR functionality.
Use Cases
[0050] HO decision algorithm [0051] The eNB may decide on the most
appropriate target cell when the UE reports more than one cell,
based on UE subscriber profile and the target cell capability
[0052] IRAT Load Balancing SON [0053] Some implementation may want
to perform IRAT Load Balancing only between LTE and HSPA cells in
order to guarantee service continuity. In this scenario, the eNB
may use this information to decide towards which cells to start the
LB measurements [0054] Load Based HO [0055] Certain implementation
may benefits from the knowledge of target cell capability in order
to segregate high rate UEs to HSPA capable UEs and voice UEs to
other target cells
Solution and Proposal
Solution
[0056] The HSDPA/E-DCH capability is broadcasted in System
Information Block type 5 and 5bis. The periodicity is configurable;
however typical value is 640 ms which fits well in the overall ANR
functionality.
[0057] The UE will report this parameter only when requested by the
eNB (FIG. 5)
Proposal
[0058] It is proposed to updates the 36.300 stage 2 specifications
to capture the above solution.
Inter-RAT/Inter-frequency Automatic Neighbour Relation Function
[0059] FIG. 6 illustrates Automatic Neighbor Relation Function in
case of UTRAN detected cell.
[0060] For Inter-RAT and Inter-Frequency ANR, each cell contains an
Inter Frequency Search list. This list contains all frequencies
that shall be searched.
[0061] For Inter-RAT cells, the NoX2 attribute in the NRT is
absent, as X2 is only defined for E-UTRAN.
[0062] The function works as follows:
[0063] The eNB serving cell A has an ANR function. During connected
mode, the eNB can instruct a UE to perform measurements and detect
cells on other RATs/frequencies. The eNB may use different policies
for instructing the UE to do measurements, and when to report them
to the eNB. [0064] 1 The eNB instructs a UE to look for neighbour
cells in the target RATs/frequencies. To do so the eNB may need to
schedule appropriate idle periods to allow the UE to scan all cells
in the target RATs/frequencies. [0065] The UE reports the PCI of
the detected cells in the target RATs/frequencies. The PCI is
defined by the carrier frequency and the Primary Scrambling Code
(PSC) in case of UTRAN FDD cell, by the carrier frequency and the
cell parameter ID in case of UTRAN TDD cell, by the Band
Indicator+BSIC+BCCH ARFCN in case of GERAN cell and by the PN
Offset in case of CDMA2000 cell. [0066] When the eNB receives UE
reports containing PCIs of cell(s) the following sequence may be
used. [0067] 3 The eNB instructs the UE, using the newly discovered
PCI as parameter, to read the CGI and the RAC of the detected
neighbour cell in case of GERAN detected cells, CGI, LAC and, RAC
in case of UTRAN detected cells and CGI in case of CDMA2000
detected cells. For the Interfrequency case, the eNB instructs the
UE, using the newly discovered PCI as parameter, to read the ECGI,
TAC and all available PLMN ID(s) of the inter-frequency detected
cell. The UE ignores transmissions from the serving cell while
finding the requested information transmitted in the broadcast
channel of the detected inter-system/inter-frequency neighbour
cell. To do so, the eNB may need to schedule appropriate idle
periods to allow the UE to read the requested information from the
broadcast channel of the detected inter-RAT/inter-frequency
neighbour cell. [0068] 4 After the UE has read the requested
information in the new cell, it reports the detected CGI and RAC
(in case of GERAN detected cells) or CGI, LAC and RAC (in case of
UTRAN detected cells) or CGI (in case of CDMA2000 detected cells)
to the serving cell eNB. In the inter-frequency case, the UE
reports the ECGI, the, tracking area code and all PLMN-ID(s) that
have been detected. [0069] 5 The eNB updates its
inter-RAT/inter-frequency Neighbour Relation Table.
[0070] In the inter-frequency case and if needed, the eNB can use
the PCI and ECGI for a new X2 interface setup towards this eNB. The
setup of the X2 interface is described in section 22.3.2.
[0071] In case of UTRAN detected cells, the eNB may request the UE
to report whether the cell is an HSPA/EDCH capable cell.
CONCLUSION
[0072] In this contribution we have proposed an enhancement of the
ANR functionality to allow the Ue to report also the target cell
capability for UTRAN cells.
[0073] Benefits and solution have been highlighted in section two
and three.
[0074] It is proposed to discuss the proposal and capture the
proposal in section 3 in stage 2 specification 36.300. It is
further proposed to send an LS to RAN2 and ask to implement the
necessary changes in the RRC specification.
[0075] This application is based upon and claims the benefit of
priority from United Kingdom Patent Application No. 0914380.1,
filed on Aug. 17, 2009, the disclosure of which is incorporated
herein in its entirety by reference.
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